The Pollen Washing Machine

If you were to ask a bee for her favorite floral confection, she’d doubtless buzz “Waterliliezzz!” with a gleam in her compound eyes.

It’s not just that waterlily fragrance is so intoxicating, and the nectar so sweet—they literally have pools  of the stuff to lure bees into their beautiful bowls.

Unlike other flowers, waterlilies are gender benders. On the first day they open, day-blooming lilies are generally female, harvesting pollen from visiting insects.

Come night, they close up, often trapping hapless stragglers and releasing them the next morning, when the lily has transformed into male, with mature stamens brushing pollen upon their insect company. This sex-changing strategy assures that no lilies self-pollinate—cross-pollinating instead to keep their chromosomes varied and strong.

The lily here appears to be on its female day, its stamens immature…

…and each stamen so flexible that it bends when a bee touches down, dumping it unceremoniously into the fluid below.

A delicious dip for the bee? Perhaps, but in reality it’s more of a washing machine cycle.

WHY? Because the waterlily’s fluid contains detergent-like surfactants that greedily strip all the pollen from each bee, after which it sinks down to the awaiting stigma, where only a granule from the same species of waterlily can fertilize and start seed production.

You can see this happening in the photograph. Look at the wet orange blob on one bee’s leg—that’s the last bits of pollen, soaked in surfactants and about to be stripped from the bee’s basket!

And this is where danger lurks. The bees here will safely crawl out of this waterlily bowl, shake their wings dry and fly home—but other insects can slip into deeper bowls and drown.

Happily, this seems the exception. Our bees will indulge their wildest candy dreams and, like Hansel and Gretel, live to tell the tale.

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